1. Field of the Invention
This invention relates to measuring and recording apparatus. More specifically, this invention relates to such apparatus which include a record inscribing means and a record retaining carrying means, one of said means being rotatable relative to the other, the other being driveable in two opposed directions, wherein, when the other means is driven in one direction, the one means rotates, whereas, when the other means is driven in the opposing direction, the one means does not rotate.
2. Statement of the Prior Art
It is known to provide instruments which measure and record two directional variables. By two directional variables is meant variables which experience increases or decreases (up and down) in their intensity or magnitude. Examples of such variables are pressure, temperature, volume, length, light intensity, speed etc.
The above mentioned instrument will have two driving means, one to drive a record inscribing means, such as a pen or stylus, and the other to drive the record retaining carrying means, such as a drum on which a paper or other recording medium is disposed. The means which drives the pen or stylus is actuated by a variable sensing transducer, and the amount and direction in which the pen or stylus is driven is a function of the magnitude and direction of the variable as sensed by the transducer. Two separate drives are required as the drive which moves the record inscribing means must be able to move in two directions, but the drive which drives the record retaining carrying means must move in one direction only.
In this regard, the prior art provides instruments for measuring and recording the level of liquid in a container.
It is known in the prior art to provide liquid level and measuring apparatus which use a float arrangement both for the purpose of detecting the level of the liquid and for driving a mechanism which either indicates or records the liquid level detected. Such apparatus are illustrated in, for example, U.S. Pat. Nos. 87,959, Minor et al, issued Mar. 16, 1869, 872,758, Runyon, issued Dec. 3, 1907, 1,208,026, Smith, issued Dec. 12, 1916, 1,336,090, Schaub, issued Apr. 6, 1920, 1,494,034, Stevens, issued May 13, 1924, 2,215,542, Chappel et al, issued Sept. 24, 1940, and 2,496,552, Lewis, issued Feb. 7, 1950 as well as in British Pat. No. 428,691, Lea, issued May 14, 1935. In all of these devices, auxiliary power means and/or clock mechanisms are required. This is expensive and the power or clock mechanisms are subject to breakdown so that there are disadvantages in the use of such devices. In addition, most of the devices record at all times that they are in operation including times when no changes are taking place, i.e., they are recording redundant information.